The present invention relates generally to vehicle frame straightening apparatus and more particularly to devices for removably securing vehicles to such apparatus.
Various apparatus are known for straightening and repairing vehicle frames. As described in U.S. Pat. Nos. 3,630,066, 3,888,100 and 4,151,737, such apparatus generally include parallel left and right treadways upon which the vehicle is positioned and suitable means such as pull towers for applying force to the vehicle frame to straighten or adjust the frame.
It is necessary to secure a vehicle to a frame straightening apparatus so that the vehicle remains fixed with respect to the treadways while the frame straightening or adjusting forces are applied to the vehicle frame. It is generally desirable that the securing device be easily adjusted so that vehicles of varying sizes can be readily accommodated. Once the vehicle is secured to the frame straightening apparatus, it is also desirable that the securing device neither interfer with nor make more difficult the operation of the frame straightening apparatus. The frame straightening forces that are applied to a vehicle can be from several directions during the straightening process as would occur, for example, with a vehicle which has sustained both front and rear frame damage. It is thus further desirable that a securing device counteract these variously applied forces without readjustment or repositioning so that the frame straightening can be more efficiently performed.
A securing device is disclosed in U.S. Pat. Nos. 3,630,066 and 3,888,100 to Chisum. The device includes a clamp which can be applied to a pinchweld of a unibody frame. A chain, which is connected at one end to the clamp, is provided at its second end with a hook which engages crossmembers within the treadway. As the frame straightening forces are applied from various directions as would occur, for example, where the forces are first applied to the front of the vehicle and then are applied to the rear of the vehicle, it is necessary to reposition the chain and the hook to provide the correct counterforce to the clamp. This is both time consuming and inconvenient. Furthermore, the chain and the hood require time consuming readjustment when side forces are applied to the vehicle to prevent the vehicle from being pulled from the treadways.
Another securing device is described in the Chisum U.S. Pat. No. 3,888,100. The device includes posts that can be inserted through openings within the treadway and which serve to anchor the chain. A disadvantage of this Chisum device is that adjustment and repositioning are required as the frame straightening forces are applied from various directions.
Another device is disclosed in U.S. Pat. No. 4,151,737 to Specktor and includes a bolster that is inserted through the treadway. The bolster includes a contacting surface and the bolster can be adjusted so that the contacting surface abuts a frame member of the vehicle to be straightened. However, as the direction of the frame straightening pulling force is changed, the bolsters must be removed and repositioned. The contacting surface of the bolsters also does not grip the vehicle frame and thus the frame can slip with respect to the bolsters if the straightening forces are not properly applied. The bolsters can also interfere with the operation of the frame straightening apparatus by, for example, obstructing the movement of the pull towers beneath the treadway.
Yet other devices are disclosed by Specktor in U.S. Pat. No. 4,138,877. These devices include a clamp which can be clamped to the pinchweld of a unibody frame, a fork and an elevated chain hook and shortener. The fork and the elevated chain hook and shortener are retained by means of an attachment member within openings in the surface member of the treadway. The clamp is then positioned to abut the fork or can be attached by means of a chain to the elevated chain hook and shortener. Also, a chain can be attached to the clamp and can be passed around a pulley within the fork so that the fork is used as a down-pull unit.
The clamp in combination with the fork or a chain and the elevated chain hook and shortener has several shortcomings. The devices must be repositioned and adjusted as the frame straightening forces are applied from various directions. Furthermore, the fork, when used as a down-pull unit, does not provide the support required when horizontal frame straightening forces are applied to the vehicle.
Therefore, there is a need for a clamping device that overcomes the limitations described above in that is easily adjusted, it does not interfere with the operation and use of the frame straightening apparatus, and it counters frame straightening forces applied from any angle without requiring adjustment or repositioning of the device.